Yeah, if this happened to me at work I'd be in a situation. First of all, I only take one break in a day...lunch which is half an hour. I bring my lunch as I work in an industrial area there are no food places...there isn't even a convenience store or anything, within walking distance. I don't have a vehicle so I can't drive anywhere so that means that if a lunch were offered, and I didn't bring lunch that day and it was cancelled or rescheduled at the last minute, I'd be pretty much screwed. Did I mention I work 10-hour days? That makes for a long, long day without a meal, since I wouldn't have had a chance to eat anything since breakfast. None of those things constitute a failure to plan.
Rude to reschedule the lunch? I don't know about rude, but it was definitely inconsiderate.